Gen3 HV Battery Capacity

Guessing here.

A Gen3 HV battery life expectancy was said to be around 100 to 150k miles, so at 80k miles that battery is roughly half way through it's life expectancy. It has thousands of tiny cells inside the battery-bank, being 'managed' by computers. I would assume that means when one cell shorts, it is isolated from the bank, so it's short does not pull down the rest of the bank. If you are half through your life expectancy, maybe half of the cells inside have been isolated from the rest. Meaning that the battery-bank's total capacity is reduced by that amount.

I bet as time goes by you could graph the loss of battery capacity. The firmware should be tracking this as a normal daily function [though I do not know how you or I would go about to see this data].

 

No, there is no "removal of bad cells" in a Prius battery. There is only checking and putting up flags if there is a problem. The HSD can see (measure) pairs of modules as I recall. That's 12 cells. One failed cell in a group of 12 is hard to see under normal operation. Hence, the dealer must run specialized checking routines to find them.

It is possible the new car has more capacity than the old one. It is also possible the old car runs the battery at lower capacity. Keep in mind, the HSD NEVER fully charges the battery. It tries to keep it at about 60% charge, but there really is no way to measure the -actual- charge level unless you were to fully discharge the battery, measuring what you took out. This would likely damage the battery, because some cells have a lower capacity than the others. They would fully discharge and be "reverse charged" if you were to try to fully discharge the battery. Reverse charging a NiMH cell will destroy it.

It is possible the cells in the older battery are no longer properly matched, and that would cause the HSD to err on the safe side and stop discharging the battery -before- the lower capacity cells fully discharge. An equalize cycle or two might correct that, but probably not, as the lower capacity is probably a physical, not chemical effect. And I know of no way to even run an equalize cycle with the battery connected to the HSD.

Bottom line, the battery is not there to use as an EV power source, it's there to make the HSD function in an integrated fashion. Except for the PIP, where there is limited EV function built in.
And no, the "EV" mode is not really there to make the Prius an EV. It's there because it could be functional in a limited way, thereby making the car more desirable (improving sales).

I wouldn't worry about it. All things manufactured will fail eventually. Be happy the 2010 is working well, if not as well as the new one.

 

do they get similar mpg's? on my '04 and '08, the mpg's never dropped noticeably, even to over 100,000 miles.

perhaps the 2010 a/c is pulling more juice.

 

how about on the '10, have the mpg's dropped?

 

well you do not have a real idea how this works obviously ...

there are not thousands of tiny cells (you can find actual pictures of disassambled HV battery)

also the battery life expectancy has NOTHING to do with miles driven rather it correlates to charge cycles ... which could be drammaticaly different among cars used differently ...

 

why, doesn't the battery contribute?

 

gotcha, thanks.

 

think about it as a buffer ... as long as the buffer is sufficient it will work ... but smaller it gets less and less benefit you will have from regenerative breaking and from starting from 0mph .... the mpg hit also depend on the actual driving pattern. One corner case is: steady highway driving 95% of the miles driven will see very little benefit/loss from battery capacity

 

i see, so the battery is sized for the worst case scenario, and most drivers pay for what they rarely/never use.

 

That is probably a little overstatement but yes ... something like that ...

The battery again is really a buffer for storing energy and depending how the given user uses the "system" the battery part will benefit that user.... There are ceartainly some driving scenarios where battery makes no or very little difference, hence not increasing efficiency (higher mpg) that much. But of course the car was probably designed for the "common" driving scenario which will cover most drivers.

My point is that lower battery capacity will be noticed differently depending on driving scenarios (including driving style, route travelled, etc)